We only have 3 Hiraganas with 2 strokes. All of them have a knot.
す【su】
Want to see the stroke order with the movie? Click here
You can easily see the stroke when you check the original Kanji.
Want to see the stroke order with the movie? Click here
み【mi】
Want to see the stroke order with the movie? Click here
I dont see well the develope from the original Kanji, anyway, it's for your reference. Just memorise the shape. You may need intensive practice to write until you'll get the balance.

Since the original Kanji means "beauty", many Japanese girls' names are used this one.
よ【yo】
Want to see the stroke order with the movie? Click here
Make sure the 2nd stroke is just touching the 1st stroke but not across.
I;m not sure the original Kanji will help you or not.
This type of stroke with knot, Top to Bottom - knot - going to right (slightly slant) can be seen in many Hiragana. For example, we've learned already ね、ぬ. We will lean the others in Lesson 15.
